Global Empirical Models for Tropopause Height Determination

Abstract

The calculation of the tropopause height is crucial to the investigation of fundamental interactions between the troposphere and stratosphere, playing an essential role in areas such as climatology, geodesy, geophysics, ecology, and aeronautics. Since the troposphere and stratosphere have many distinct features, it is possible to define the boundary between them using different variables, such as temperature lapse rate, potential vorticity and chemical concentrations. However, according to the chosen variable, different tropopause definitions are created, each one with some limitations. Using 41 years of European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) data, we examined the variability of the tropopause for the north and south hemispheres and developed two models, both based on blending the potential vorticity and thermal tropopauses. One model (based on a sigmoid function, named STH) depends only on latitude and day of the year, while the other model (based on bilinear interpolation, named BTH) requires an additional look-up table. In order to account for the different behaviors of the tropopauses in the north and south hemispheres, we estimated two sets of model coefficients (one for each hemisphere). When compared against a benchmark of estimated tropopause heights during three years of radiosonde data, we obtained an average RMSE for the differences of 0.88 km for the STH model and 0.67 km for the BTH model. A similar comparison for alternative models available in the literature shows that the new models have superior performance and represent a significant improvement in tropopause height determination.

Tropopause folds over the Tibetan Plateau and their impact on water vapor in the upper troposphere-lower stratosphere

“…In the northern hemisphere, the dynamical tropopause is de ned by PV values in the range of 1-4 PVU (1 (Kunz et al 2011). A de nition of the blended tropopause combines the characteristics of both dynamical and thermal tropopause (Wilcox et al 2012;Mateus et al 2022). In this paper, the dynamical tropopause is de ned as the lower height of the isosurface of PV at 2 PVU and isentropic surface at θ = 380 K (Hoskins et al 1985;Holton et al 1995 shown in Fig.…”

Evaluation of Tropopause Height from Sentinel-6 GNSS Radio Occultation Using Different Methods

“…Additionally, the tropopause serves as the upper limit for the integration of tropospheric parameters in physics and chemistry, including tropospheric temperature [11] and tropospheric column ozone [12]. The TPH can be determined from the use of radiosonde data [7,[13][14][15] or from Global Navigation Satellite System (GNSS) radio occultation (RO) data from different satellites [5,[16][17][18][19][20][21][22][23][24][25].…”

“…be determined from the use of radiosonde data [7,[13][14][15] or from Global Navigation Satellite System (GNSS) radio occultation (RO) data from different satellites [5,[16][17][18][19][20][21][22][23][24][25].…”